The script you're loading is just turning right around and using XMLHttpRequest to load another one (also from js.authorize.net); that request is being denied because your page's origin isn't allowed access. Looks like some kind of authorization thing to keep their JS from being downloaded on unauthorized origins.

Nothing you do on your end changes the CORS rules at the js.authorize.net end. It's that server, js.authorize.net, that has to allow your origin to do the request.

You'll need to work with the people behind js.authorize.net in order to get access.